Math disability (MD) and reading disability (RD) have a significant negative impact at the individual and societal levels. Co-existence of the two (MD+RD) is an even greater challenge and presents an urgent problem for researchers and practitioners to address. The neural correlates of successful math and reading interventions in children with comorbid MD+RD are unknown, yet this knowledge would provide important insights into MD+RD and its remediation. We will investigate reading- and math-specific intervention-induced brain changes and test the hypothesis that reading and retrieval-based arithmetic, because verbally mediated, are both strengthened through reading intervention. Using functional magnetic resonance imaging (fMRI) methods employed in our prior studies, we propose to examine brain areas that subserve (i) reading, (ii) verbally mediated, retrieval- based arithmetic (addition of small numbers), and (iii) procedural-based arithmetic (subtraction). Forty-eight children with MD+RD will be studied prior to and following two periods of intensive tutoring: math followed by reading intervention, or vice versa. Following each intervention, we will examine reading and math performance via neuropsychological measures and brain-based changes (activity during reading and retrieval- based/procedural-based math tasks, resting state connectivity, and brain anatomy). Our first Aim is to test whether reading intervention brings about gains not only in reading (concomitant with left hemisphere increases in brain activity during reading), but also in math performance, and that these reading-intervention- induced changes in math also elicit increases during retrieval-based arithmetic in the same left hemisphere regions subserved by language. We also expect that math intervention results in gains on standardized and experimental measures of math along with increased brain activity, this time in right hemisphere parietal cortex during procedural-based arithmetic. As such, we will test the role of language mediation in the remediation of MD+RD by manipulating both the type of intervention and the fMRI tasks. We will employ analysis techniques that will allow us to assess brain-behavioral and brain-brain relationships prior to and following interventions. In our second Aim, we will test whether brain activity during reading and math tasks prior to the interventions predicts the improvements in reading and math skills, with the hypothesis that left inferior parietal cortex plays a critical role in signaling a verbally mediated readiness to maximally benefit from either intervention. In a third Aim, we will pool the fMRI data on tasks prior to the intervention with the same type of data previously acquired in children with RD and controls. In this sample of 120, we will examine relationships between neuropsychological measures of reading, phonological, and math skills, with brain activity during reading and math. This will allow us to test relationships described above between math, language, and brain function using a wider continuum. Together, these aims directly fit FOA PA-12-248 by addressing math learning, math disabilities, language influence on math, and intervention-induced neurobiological plasticity.